Detroit's Unsold Cars Pile Up

By

Jeff Bennett And

Christina Rogers

Updated Dec. 5, 2012 3:57 p.m. ET

Detroit auto makers are piling up big stocks of passenger cars at dealers despite brisk new-vehicle sales in the U.S.—a problem that executives vowed to avoid since their painful downturn three years ago.

General Motors Co. ended November with enough Malibu sedans and Camaro sports cars to last more than five months at the current rate of sales. Ford Motor Co. had more than four months' worth of Fiesta subcompacts and Chrysler...